Japan says its exports fell 10 percent from a year earlier in April and imports plunged 23 percent, as a monthly survey of factory managers showed the sharpest worsening in operating conditions in over three years.

Customs figures released Monday show Japan posted a trade surplus of 823 billion yen ($9.1 billion) in April, compared with a deficit of 58.3 billion yen a year earlier.

A stronger Japanese yen exaggerated the decline in exports, but shipments fell in volume terms, too.

The key figure in a monthly survey of factory managers fell to 47.6 in May from 48.2 in April. A reading of 50 marks the line between contraction and expansion.

Economists said the latest data suggest exports will fall further in the current quarter.